I'm aware of the rationale for all the record-keeping now, but I don't understand why the purchase of a single box would invite so much scrutiny and suspicion.

I don't get it either. The reason it continues to be sold at all is, hey, it's an effective drug with a legitimate use.

I mean, if someone wants to buy out the store's entire stock, that's an eyebrow raiser at the very least. But if someone wants a single box, don't make the poor bastard dealing with a cold go through any more trouble than he has to.